The term means the primal source from which all things originate, both animate and inanimate, including human beings. Yuan (元) manifests itself in different forms. In the Han Dynasty, it was considered a kind of primal physical material that both produced and made up the myriad things of the world. The Book of Changes divides yuan into two primal sources: the heavenly source which gives birth to the sun, moon, and stars, and the earthly source which creates all other things on earth. In The Spring and Autumn Annals, the term refers to the first year in its chronologies, symbolizing the start of a new historical period, and serving as the manifestation in the human world of the natural process in which things begin, end, and are replaced.